From the link you posted:

“Game-key cards are different from regular game cards, because they don’t contain the full game data. Instead, the game-key card is your "key" to downloading the full game to your system via the internet.

After it’s downloaded, you can play the game by inserting the game-key card into your system and starting it up like a standard physical game card. An internet connection is only required when you launch the game for the first time. After this, the game can be started even without an internet connection. However, like regular physical software, the game-key card must be inserted into the system in order to play the game. A Nintendo Account is not required to download the game data.”

So lending and reselling game-key cards is still possible in the same way as physical media… at least until Nintendo’s servers stop serving the game, heh.

They're theoretically a tiny bit better than download codes, but the same applies. If this is the format going forward, I'm out.